In our home network, we have 3 XP machines & one Mac. We all have the PC's Firewall setting activated. I use Nod 32 on mine, the other PC's use AVG. the Mac- none. None of us have any sharing settings activated. The one Mac and one PC is a Notebook. I am pretty careful on my PC, but what if one of my kids, either at home or at Starbucks, gets an infection. Can a virus spread to all machines? Should my kids NOT check their e-mails at Starbucks?